19 research outputs found
On Buffer-Aided Multiple-Access Relay Channel
The paper treats uplink scenario where M user equipments (UEs) send to a Base
Station (BS), possibly via a common Relay Station (RS) that is equipped with a
buffer. This is a multiple-access relay channel (MARC) aided by a buffer. We
devise a protocol in which the transmission mode is selected adaptively, using
the buffer at the RS in order to maximize the average system throughput. We
consider the general case in which the RS and the BS can have limits on the
maximal number of transmitters that can be received over the multiple access
channel. In each slot there are three type possible actions: (A1) multiple UEs
transmit at rates that enable BS to decode them (A2) multiple UEs transmit, the
BS can only decode the messages partially, while the RS completely; (A3) RS
forwards the side information to BS about the partially decoded messages, which
are going to be combined and decoded entirely at the BS, while simultaneously a
number of UEs sends new messages to the BS. The results show that the adaptive
selection of direct and buffer-aided relay transmissions leads to significant
average throughput gains.Comment: 13 pages, 3 figures, accepted to IEEE Communications letter
Decoupled Uplink and Downlink in a Wireless System with Buffer-Aided Relaying
The paper treats a multiuser relay scenario where multiple user equipments
(UEs) have a two-way communication with a common Base Station (BS) in the
presence of a buffer-equipped Relay Station (RS). Each of the uplink (UL) and
downlink (DL) transmission can take place over a direct or over a relayed path.
Traditionally, the UL and the DL path of a given two-way link are coupled, that
is, either both are direct links or both are relayed links. By removing the
restriction for coupling, one opens the design space for a decoupled two-way
links. Following this, we devise two protocols: orthogonal decoupled UL/DL
buffer-aided (ODBA) relaying protocol and non-orthogonal decoupled UL/DL
buffer-aided (NODBA) relaying protocol. In NODBA, the receiver can use
successive interference cancellation (SIC) to extract the desired signal from a
collision between UL and DL signals. For both protocols, we characterize the
transmission decision policies in terms of maximization of the average two-way
sum rate of the system. The numerical results show that decoupling association
and non-orthogonal radio access lead to significant throughput gains for
two-way traffic.Comment: 27 pages, 10 figures, submitted to IEEE Transactions on
Communication
Ultra-Reliable Low Latency Communication (URLLC) using Interface Diversity
An important ingredient of the future 5G systems will be Ultra-Reliable
Low-Latency Communication (URLLC). A way to offer URLLC without intervention in
the baseband/PHY layer design is to use interface diversity and integrate
multiple communication interfaces, each interface based on a different
technology. In this work, we propose to use coding to seamlessly distribute
coded payload and redundancy data across multiple available communication
interfaces. We formulate an optimization problem to find the payload allocation
weights that maximize the reliability at specific target latency values. In
order to estimate the performance in terms of latency and reliability of such
an integrated communication system, we propose an analysis framework that
combines traditional reliability models with technology-specific latency
probability distributions. Our model is capable to account for failure
correlation among interfaces/technologies. By considering different scenarios,
we find that optimized strategies can in some cases significantly outperform
strategies based on -out-of- erasure codes, where the latter do not
account for the characteristics of the different interfaces. The model has been
validated through simulation and is supported by experimental results.Comment: Accepted for IEEE Transactions on Communication
Optimized Interface Diversity for Ultra-Reliable Low Latency Communication (URLLC)
An important ingredient of the future 5G systems will be Ultra-Reliable
Low-Latency Communication (URLLC). A way to offer URLLC without intervention in
the baseband/PHY layer design is to use \emph{interface diversity} and
integrate multiple communication interfaces, each interface based on a
different technology. Our approach is to use coding to seamlessly distribute
coded payload and redundancy data across multiple available communication
interfaces. We formulate an optimization problem to find the payload allocation
weights that maximize the reliability at specific target latency values. By
considering different scenarios, we find that optimized strategies can
significantly outperform -out-of- strategies, where the latter do not
account for the characteristics of the different interfaces. Our approach is
supported by experimental results.Comment: Presented in Globecom'1
Backscattering Estimation of a Tilted Spherical Cap for Different Kinds of Optical Scattering
In many optical engineering applications, a spherical cap shaped optical element is widely used such as concave or convex mirrors in reflective optics. Such an element can also tilt around the vertex which corresponds to an off-axis optical design. The optical backscattering of such an optical element sometimes could be important. For example, in the space-based gravitational wave detection, the backscattering of such an element could be superimposed with the local oscillator and limits the sensitivity of the spacecraft. The scattered contributions depend on the scattering property of the mirror surfaces and the geometrical arrangement including the radius of curvature, the tilt and the interval between the scattering source and detector plane. Based on random estimation method, this paper starts from the radiometry, combines these variables and calculates the theoretical amount of back scattered light for both diffuse and superpolished surfaces. The results are compared with analytical and ray tracing solution. The conclusions can be used to further improve the optical design of the telescope or extended to other cases where the backscattered light should be controlled
Backscattering Estimation of a Tilted Spherical Cap for Different Kinds of Optical Scattering
In many optical engineering applications, a spherical cap shaped optical element is widely used such as concave or convex mirrors in reflective optics. Such an element can also tilt around the vertex which corresponds to an off-axis optical design. The optical backscattering of such an optical element sometimes could be important. For example, in the space-based gravitational wave detection, the backscattering of such an element could be superimposed with the local oscillator and limits the sensitivity of the spacecraft. The scattered contributions depend on the scattering property of the mirror surfaces and the geometrical arrangement including the radius of curvature, the tilt and the interval between the scattering source and detector plane. Based on random estimation method, this paper starts from the radiometry, combines these variables and calculates the theoretical amount of back scattered light for both diffuse and superpolished surfaces. The results are compared with analytical and ray tracing solution. The conclusions can be used to further improve the optical design of the telescope or extended to other cases where the backscattered light should be controlled
Shizukaol D inhibits lipid accumulation in HepG2 cells in an AMPK-dependent manner.
<p>HepG2 cells were transfected with AMPK siRNA or a control siRNA for 24 h followed by incubation with 2 µM shizukaol D or 2 mM metformin for an additional 24 h. AMPK and ACC phosphorylation was analyzed by western blotting (A), and the triglyceride content (B) and cholesterol content (C) were measured (n = 3). (D) The cells were pretreated with 20 µM compound C (an AMPK inhibitor) followed by treatment with 2 µM shizukaol D. AMPK and ACC phosphorylation was analyzed by western blotting (D), and the triglyceride content (E) and cholesterol content (F) were measured (n = 3). Statistical analysis was performed using two-way ANOVA followed by Tukey’ post-hoc test *, p<0.05; **, p<0.01.</p